Dual cam trigger for a surgical instrument

ABSTRACT

The present invention is directed to a surgical instrument such as, for example, an ultrasonic surgical cutting and coagulating device, wherein the gripping movement of the surgeon is mechanically translated into lateral movement for actuating, for example, an actuating rod. One embodiment of the present invention includes a camming pivot for use in surgical instruments, wherein the camming pivot comprises an actuation mechanism, including; a lever arm; a first cam at a distal end of the lever arm; and a second cam positioned distally from the first cam.

This application is a continuation of Ser. No. 09/353,482 filed Jul. 13,1999 now abandoned, which is a continuation of Ser. No. 08/947,690 filedOct. 9, 1997 now U.S. Pat. No. 5,954,746.

FIELD OF THE INVENTION

The present invention relates, in general, to an improved handle forsurgical instruments and, more particularly, to an improved scissor typehandle wherein the movable handle element is attached to the body of theinstrument by a camming mechanisim including a first cam and a secondcam.

BACKGROUND OF THE INVENTION

U.S. Pat. No. 322,055 describes an ultrasonic surgical apparatus whichincludes a surgical instrument having a handpiece with a transducer forconverting an electrical signal into longitudinal vibratory motion. Thelongitudinal vibratory motion is transmitted to an ultrasonic bladewhich is connected to the handpiece. An accessory is releasablyconnected to the handpiece to enable clamping of tissue against thevibrating blade to afford improved coagulating and cutting of tissue. InU.S. Pat. No. 5,322,055 Scissors-like grips actuate a pivoted clamp jawalong one side of the ultrasonically vibrating blade to compress andbias tissue against the blade in a direction which is substantiallynormal to the direction of longitudinal vibratory movement. In U.S. Pat.No. 5,322,055, the clamp jaw and blade are rotatable relative to oneanother to align a selected blade edge of a multi-edged blade with theclamp jaw for cutting and coagulating while clamping orcircumferentially spacing a selected blade edge from the clamp jaw forcutting and coagulating without clamping. U.S. Pat. No. 5,322,055 ishereby incorporated herein by reference.

Many surgical instruments, such as the ultrasonic surgical deviceillustrated and descried in U.S. Pat. No. 5,322,055, use elements suchas actuation rods to transmit force from the proximal end of theinstrument, where the instrument is gripped by the surgeon, to thedistal end of the instrument where the transmitted force is used toactuate an end effector such as, for example, a clamping jaw. In orderto effectively transmit force from the surgeons hand to the end effectorin such an instrument, it is necessary to translate the grasping motionof the surgeons fingers to the lateral motion of the actuation rod.Scissors type grips are used in many surgical devices of this kindbecause they are comfortable and tend to be familiar to the surgeon.Many such instruments use a single pivot pin in combination with a camof some type to translate the arcuate motion of the scissor grip to thelinear motion of the actuation rod. However, in certain circumstances,such an arrangement may not be acceptable, such as, for example, wherethe room in the instrument body is limited and rotational movement ofthe grip around a fixed pivot pin requires too much of the availableroom. Further, in order to increase the stroke in pivot pin arrangement,it is generally necessary to increase the distance from the pivot pin tothe cam, requiring more room if a longer stroke is desired. It would,therefore, be advantageous to provide an improved actuation mechanismfor translating the grasping motion of a human hand to the lateralmotion necessary to drive an actuation rod. In particular, it would beadvantageous to provide such an improved actuation mechanism withoutusing a fixed pivot pin type arrangement. It would also be advantageousto provide such an improved actuation mechanism in an in line handlearrangement and to reduce the room necessary for the actuation mechanismwithout substantially reducing the stroke length of the actuation rod.

SUMMARY OF THE INVENTION

The present invention is directed to a surgical instrument such as, forexample, an ultrasonic surgical cutting and coagulating device, whereinthe gripping movement of the surgeon is mechanically translated intolateral movement to move, for example, an actuating rod. One embodimentof the present invention includes a camming pivot for use in surgicalinstruments, wherein the camming pivot includes: a lever arm; a firstcam at a distal end of the lever arm; and a second cam positioneddistally from the first cam. In one embodiment of the present invention,the first and second cams may comprise, for example, camming pivot pinsmoveable within first and second camming slots. In a further embodimentof the invention, the first camming slot may include a curved or angularinterior camming surface.

In a further embodiment of the present invention, a surgical deviceincludes an end effector, a camming pivot actuation mechanism and anactuation rod connecting the end effector to the actuation mechanism. Insuch an instrument, the actuation rod is gennerally positionedsubstantially parallel to the central axis of the instrument. The endeffector may include, for example, an ultrasonic blade and a movableclamping element disposed opposite the ultrasonic blade. The actuationmechanism, which is operatively connected to the moveable clampingelement by, for example, the actuation rod, may include a lever arm andfirst and second cams at a distal end of the lever arm. In thisembodiment of the invention, the first cam may comprise, for example, afirst camming pin positioned on the lever arm and a first camming slotoperatively associated with the first camming pin where in the firstcamming slot is positioned at an angle to the central axis of theinstrument. The second cam may comprise, for example, a second cammingpin positioned on the lever arm distally from the first cam and a secondcamming slot operatively associated with the second camming pin, withthe second camming slot being positioned substantially parallel to thecentral axis of the instrument.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe appended claims. The invention itself, however, both as toorganization and methods of operation, together with further objects andadvantages thereof, may best be understood by reference to the followingdescription, taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is an isometric view of an ultrasonic surgical device constructedin accordance with a preferred embodiment of the present invention.

FIG. 1A is a centerline section view of the handle portion of theinstrument of FIG. 1.

FIG. 2 is an isometric view of a clamp coagulator accessory according tothe present invention.

FIG. 3 is an exploded isometric view of the clamp coagulator accessoryillustrated in FIG. 2.

FIG. 4 is a plan view of the right hand portion of the housing of theclamp coagulator accessory partially broken away for clarity.

FIG. 5 is a centerline side elevation view of the right hand housing ofthe clamp coagulator accessory.

FIG. 6 is an enlarged fragmentary isometric view of the distal portionof the right hand housing of the clamp coagulator accessory.

FIG. 7 is a side elevation view of the clamp jaw actuation mechanism ofthe clamp coagulator accessory.

FIG. 8 is a bottom plan view of the clamp jaw actuation mechanism of theclamp coagulator accessory.

FIG. 9 is an enlarged centerline section view of a portion of the clampcoagulator accessory with the clamp jaw actuation mechanism 26 a closedposition.

FIG. 10 is an enlarged centerline section view of a portion of the clampcoagulator accessory with the clamp jaw actuation mechanism in an openposition.

FIG. 11 is a centerline side elevation view of the right hand housing ofthe clamp coagulator accessory according to a further embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is an isometric view of an ultrasonic surgical device constructedin accordance with a preferred embodiment of the present invention. FIG.1A is a centerline section view of the handle portion of the instrumentof FIG. 1. In FIGS. 1 and 1A ultrasonic surgical device 10 includes anultrasonic surgical instrument 16 and a clamp coagulator accessory 12.Ultrasonic instrument 16 comprises a housing or handpiece 14 incombination with an ultrasonic blade 20 and, in some embodiments, ablade coupler extension which connects handpiece 14 to blade 20.Handpiece 14 houses a transducer (not shown), preferably a piezeoceramictransducer, for converting an electrical signal, for example, a 55,000Hz sinusoidal waveform, into a mechanical longitudinal vibration. Asdescribed in detail in U.S. Pat. No. 5,322,055, which was previouslyincorporated herein by reference, surgical instrument 10 includes ablade coupler extension 18 which extends from housing 14 throughelongated tube 22 and carries ultrasonic blade 20. Thus, ultrasonicvibrations are transmitted from the transducer in handpiece 14,longitudinally along the blade coupler extension 18 to blade 20. InFIGS. 1 and 1A, elongated tube 22 surrounds the blade coupler extension18.

FIG. 2 is an isometric view of a clamp coagulator accessory according tothe present invention. In FIG. 2, clamp coagulator accessory 12 includesan elongated tube 22 pivotally carrying a clamping jaw 24 at its distalend and a clamp jaw actuation mechanism 26 at its proximal end.Accessory 12 also includes accessory housing 28 which supports clamp jawactuation mechanism 26 and elongated tube 22. Accessory housing 24further supports rotation control knob 61 which includes mounting lever42. Accessory housing 28 further includes a generally cylindricalfitting having a proximal axial bore 40 for receiving the distal end ofhandpiece 14. In the embodiment of the invention illustrated anddescribed herein, finger ring 71 is affixed to and suported by accessoryhousing 28.

FIG. 3 is an exploded isometric view of the clamp coagulator accessoryillustrated in FIG. 2. As illustrated in FIG. 3, elongated tube 22 has afirst axial bore 48 and a second axial bore 50. First axial bore 48carries an actuating rod 52 for actuating clamp jaw 24. When clampcoagulator accessory 12 is mounted to ultrasonic surgical instrument 16as illustrated in FIG. 1, second axial bore 50 receives ultrasonic blade20, which is mounted on blade coupler extension 18. Thus, a clampcoagulator accessory such as clamp coagulator accessory 12 may be fittedover an ultrasonic instrument such as ultrasonic surgical instrument 16to form ultrasonic surgical device 10. Mounting lever 42 is pivotallymounted by lever mounting pin 43 to rotation control knob 61, which alsoincludes compression pad 44. Rotation control knob 61 is divided intotwo parts for ease of manufacture. Lever mounting assembly 58, whichincludes pivot pin holes 60 and knob positioning slots 59, snaps intothumb wheel 62 to form rotation control knob 61. When clamp coagulatoraccessory 12 is assembled, tube 22 is suitably fixed to accessoryhousing 28.

In FIG. 3, actuation rod 52 is slideably positioned in first axial bore48 with wireform 86 positioned in opening 87. Shim 88, which may beconstructed of, for example, silicone, is positioned in slot 91 suchthat actuation rod 52 passes through shim 88 as it moves in axial bore48. At its distal end, elongated tube 22 includes support bushing 94which may be constructed of, for example, Teflon. Clamping jaw 24 isaffixed to elongated tube 22 by jaw pivot pin 90 which is positioned inpivot pin guide hole 92. Elongated tube 22 further includes alignmentguide hole 100 which is adapted to receive alignment pin 98.

Clamp jaw actuation mechanism 26 is illustrated in FIG. 3 and furtherillustrated in greater detail in FIGS. 7 and 8. FIG. 7 is a sideelevation view of the clamp jaw actuation mechanism of the clampcoagulator accessory. FIG. 8 is a bottom plan view of the clamp jawactuation mechanism of the clamp coagulator accessory. Clamp jawactuation mechanism 26 includes thumb ring 70 at its proximal end. Thumbring 70 is connected to a first camming pin 74 and a second camming pin76 by lever arm 72. Rotation locking flange 78 extends from the innersurface of lever arm 72. Notch 84, which is designed to receive wireform 86, is positioned at the distal end of lever arm 72.

FIG. 4 is a plan view of the right hand portion of the housing of theclamp coagulator accessory partially broken away for clarity. FIG. 5 isa centerline side elevation view of the right hand housing of the clampcoagulator accessory. FIG. 6 is an enlarged fragmentary isometric viewof the distal portion of the right hand housing of the clamp coagulatoraccessory. As illustrated in FIG. 3 and in greater detail in FIGS. 5 and6, accessory housing 28 includes detent flanges 30, first cammingchannel 54 and second camming channel 56. First camming channel 54 andsecond camming channel 56 are positioned and adapted to receive firstcamming pin 74 and second camming pin 76 respectively. It will beapparent that, in the embodiment of the invention described andillustrated herein, both halves of accessory housing 28 will prefeablyinclude both first camming channel 54 and second camming channel 56.However, in other embodiments of the present invention, it may be enoughto include camming channels on only one half of accessory housing 28 orto include first camming channel 54 on one half of housing 28 and secondcamming channel 56 on the other half of housing 28.

FIG. 11 is a centerline side elevation view of the right hand housing ofthe clamp coagulator accessory according to a further embodiment of thepresent invention. In the embodiment of the invention illustrated inFIG. 11, first camming slot 54 includes a first interior camming surface64 which is substantially convex in shape. In this embodiment, firstcamming slot 54 further includes a second camming surface 65 which issubstantially concave in shape. Thus, in the embodiment of FIG. 11,first camming slot 54 is substantially arcuate in shape.

In operation, it will be appreciated that ultrasonic surgical instrument16 may be used with or without a blade coupler extension 18 for cuttingand coagulating in a conventional manner. Likewise, clamping jaw 24 maybe disposed directly on accessory housing 28 depending upon the desiredlength of the resulting surgical device. Thus, a surgical device 10according to the present invention may be provided in different lengthsfor different surgical purposes. For endoscopic, particularlylaparoscopic use, extension 18 is applied to the handpiece 14 and theaccessory 12 includes elongated tube 22 housing blade coupler extension18. Thus, in the illustrated form, ultrasonic surgical device 10 and,more particularly, clamp coagulator accessory 12 are adapted for use ineither laparoscopic or open surgery. Blade coupler extension 18 carriesa plurality of longitudinally spaced rings 15, preferably formed ofsilicone, located at the node points of the blade coupler extension 18to minimize or eliminate dissipation of the ultrasonic longitudinalvibration of the blade coupler extension 18 by contact with the innersurface of second axial bore 50 of tube 22.

Attachment of ultrasonic surgical instrument 16 to clamp coagulatoraccessory 12 is accomplished using mounting lever 42 which, when closed,compresses clamp pad 44 against the outer surface of housing 14 forfrictional engagement along the outer surface of the distal end ofhandpiece 14. Thus, rotational control knob 61 of accessory 12 andhandpiece 14 are frictionally attached one to the other againstlongitudinal and rotational movement. Mounting lever 42 operates as anover-center toggle and pivots between accessory mounting and demountingpositions relative to handpiece 14, as illustrated by the full anddashed lines in FIG. 1.

In order to ensure that ultrasonic blade 20 is properly aligned withclamping jaw 24 when clamping jaw 24 is closed, knob positioning slots59 on rotation control knob 61 are positioned opposite rotation lockingflange 78 when clamp jaw actuation mechanism 26 is opened and closed.Detent flanges 30 on accessory housing 28 are used to assist in aligningknob positioning slots 59 with rotation locking flange 78. Detentflanges 30 extend from accessory hosing 28 and are arranged to engagedetents (not shown) in the distal end of rotation control knob 61. Thus,with detent flanges 30 positioned in the appropriate detents in controlknob 61, knob positioning slots 59 will be aligned to receive rotationlocking flange 78. Further, when rotation locking flange 78 ispositioned in one of knob positioning slots 59, rotation control knoband blade 20 are locked in position and cannot be moved relative toaccessory housing 28 and clamping jaw 24 respectivly.

Operation of the invention may best be understood with reference toFIGS. 1-10 and, in particular, to FIGS. 9 and 10. FIG. 9 is an enlargedcenterline section view of a portion of clamp coagulator accessory 12with clamp jaw actuation mechanism 26 in a first, closed position whichcorresponds to clamping jaw 24 in its clamped or closed position. FIG.10 is an enlarged centerline section view of a portion of clampcoagulator accessory 12 with clamp jaw actuation mechanism 26 in asecond, open position which corresponds to clamping jaw 24 in itsunclamped or open position. In operation, movement of clamp jawactuation mechanism 26 from its first, closed position (as illustratedin FIG. 9) to its second, open position (as illustrated in FIG. 10)results in movement of clamping jaw 24 from its closed position to itsopen position. Conversely, movement of clamp jaw actuation mechanism 26from its second, open position (as illustrated in FIG. 10) to its first,closed position (as illustrated in FIG. 10) results in movement ofclamping jaw 24 from its closed position to its open position.

As illustrated in FIG. 9, with clamp jaw actuation mechanism 26 in itsfirst, closed position, camming pins 74 and 76 are at the distal mostpoint of their travel and notch 84 is at the distal most point of itstravel. Thus, in FIG. 9, actuation rod 52 has been pushed distally alongfirst axial bore 48 by the interaction of notch 84 and wireform 86. Shim88 acts to add drag to the movement of actuation rod 52, improving thefeel of the device. Actuation rod 52, being connected to clamping jaw 24by jaw hook 89, pushes on clamping jaw 24, which pivots around jaw pivotpin 90 to its closed position. As illustrated in FIG. 10, with clamp jawactuation mechanism 26 in its second, open position, camming pins 74 and76 are at the proximal most point of their travel and notch 84 is at theproximal most point of its travel. Thus, in FIG. 9, actuation rod 52 hasbeen pulled proximally along first axial bore 48 by the interaction ofnotch 84 and wireform 86. Actuation rod 52, being connected to clampingjaw 24 by jaw hook 89, pulls on clamping jaw 24, which pivots around jawpivot pin 90 to its open position.

As clamp jaw actuation mechanism 26 moves from its first, closedposition to its second, open position, camming pins 74 and 76 move alongcamming channels 54 and 56 respectively. Thus, the substantially arcuatemotion of actuation mechanism 26 is translated into the substantiallylinear motion of notch 84 which, in turn, moves actuation rod 52 alongfirst axial bore 48. In the embodiment of the invention illustrated inFIGS. 9 and 10, first camming channel 54 and first camming pin 74comprise first cam 32. Further, in that embodiment, second cammingchannel 56 and second camming pin 74 comprise second cam 34. First cam32 and second cam 34 act as a mechanical linkage which transforms thearcuate or rotary motion of actuation mechanism 26 into thesubstantially linear motion of notch 84. Thus, in, for example, cam 32,first camming pin 74 rotates and slides within first camming slot 54while, in cam 34, second camming pin 76 rotates and slides within secondcamming slot 56. Other camming arrangements may be suitable for use inthe present invention. For example, it will be apparent that, for thepurposes of the present invention, it is not necessary to have cammingchannels on both halves of housing 28 or to have camming pins on bothsides of clamp jaw actuation mechanism 26. A first cam 32 and a secondcam 34 positioned on one side of accessory housing 28 or a first cam 32on a first side of accessory housing 28 and a second cam 34 on a secondside of housing 28 would also function in accordance with the presentinvention. Further, by incorporating one or both of the camming slotsinto jaw actuation mechanism 26, each cam may comprise a single cammingpin extending from one side of housing 28 to the other side, passingthrough the camming slots in jaw actuation mechanism 26.

In the embodiment of the invention illustrated in FIG. 11, firstinterior camming surface 64 being substantially convex and secondinterior camming surface 65 being substantially concave, first cammingchannel is substantially arcuate in shape. Thus, in the embodiment ofFIG. 11, first camming pin 74 will move in an arc as clamp jaw actuationmechanism 26 is opened and closed. By using an arcuate shape for firstcamming channel 54, the stroke length of actuation rod 52 may beincreased more than the corresponding increase in the travel of thumbring 70 ensuing that clamping jaw 24 may be opened to a desired gapwhile keeping the travel of thumb ring 70, within a range which iscomfortable for the surgeon operator. It will be apparent that the useof various shapes for first camming channel 54 may provide a number ofadvantages in stroke length and force transmission, depending upon theshape chosen. It will also be apparent that various shapes may be chosenwithout departing from the scope of the present invention, including,for example, an angular camming channel with a bend between the open andthe closed position to change the mechanical advantage (i.e. the percentof force exerted on clamp jaw actuation mechanism 26 which istransmitted to clamping jaw 24) over the range of travel of clamp jawactuation mechanism 26. For example, it may be advantageous if a smallerpercent of the force exerted is applied during the last portion of theclosing stroke.

For the purposes of the present invention, the interior angle which isformed at the intersection of the cam tangent line with the central axisof the medical instrument in question may be referred to as the cammingangle. The cam tangent line is a line which is parallel to the proximalmost elongated wall of the proximal most camming slot or, in the case ofa curved or angular slot, which tangential to the distal most point ofthe proximal most elongated wall of the proximal most camming slot. Thecentral axis of the medical instrument is a line running through theinstrument which is substantially parallel to the centerline of theinstrument. For the purposes of the present invention, the central axismay be defined as a line which is substantially parallel to theactuation rod. Finally, the interior angle is the proximal most angle atthe intersection of the target line with the central axis.

In the clamp jaw actuation mechanism illustrated in FIGS. 1-10 and, moreparticularly in FIG. 9, the cam tangent line is a line which is parallelto proximal most elongated wall 66 of slot 54. The central axis is aline running parallel to actuating rod 52. The angle 67 formed by theintersection of the cam tangent line and the central axis is the camangle. In the clamp jaw actuation mechanism illustrated in FIG. 11, thecam tangent line is a line parallel to a line running through slot 54which is tangential to distal most point 68 of first interior cammingsurface 64. Thus, in the embodiment of FIG. 11, the angle 67 formed bythe intersection of the cam tangent line and the central axis is the camangle. For the purposes of the present invention, the camming angle isgenerally greater than 20 degrees.

It will be apparent that an actuation mechanism according to the presentinvention may be used with any number of surgical instruments, and, inparticular, in any surgical instrument where an actuation rod is used todrive one or more elements of an end effector. Such surgical instrumentsmay include, for example; scissors, graspers, forceps, clamps,electrosurgical devices or other devices. It will also be apparent thatthe present invention may be incorporated into a number of jaw closurearrangements. For example, in certain embodiments of the presentinvention, alternate elements may be substituted for the actuation rod,in particular, in a device according to the present invention which usesa tube closure mechanism, the moveable tube may be substituted for theactuation rod.

While preferred embodiments of the present invention have been shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the invention. Accordingly, it isintended that the invention be limited only by the spirit and scope ofthe appended claims.

What is claimed is:`
 1. A surgical instrument including an actuationmechanism for actuating an end effector at a distal end of said surgicalinstrument, wherein said actuation mechanism comprises: a) a cammingpivot, wherein said camming pivot comprises: i) a lever arm having afirst position and a second position ii) a first cam at a distal end ofsaid lever arm, said first cam comprising: A) a first camming pin; B) afirst camming slot operatively associated with said first camming pin;iii) a second cam positioned distally from said first cam, said secondcam comprising: A) a second camming pin; B) a second camming slotoperatively associated with said second camming pin; b) an actuation rodoperatively coupled to said camming pivot and moveable from a firstdistal postion to a second distal position corresponding to the firstand second position.
 2. A surgical instrument according to claim 1wherein said first camming slot is curved.
 3. A surgical instrumentincluding a camming pivot, wherein said camming pivot comprises: a) anactuation mechanism, wherein said actuation mechanism comprises: i) alever arm having a first position and a second position; ii) a first camat a distal end of said lever arm, said first cam comprising: A) a firstcamming pin positioned on said lever arm; B) a first camming slotoperatively associated with said first camming pin where in said firstcamming slot is positioned at a cam angle of greater than approximatelytwenty degrees; iii) a second cam positioned distally from said firstcam, said second cam comprising: A) a second camming pin positioned onsaid lever arm; B) a second camming slot operatively associated withsaid second camming pin wherein said second camming slot issubstantially parallel to a central axis of said surgical instrument; b)an actuation rod operatively coupled to said actuation mechanism andmoveable from a first distal postion to a second distal positioncorresponding to the first and second positions.
 4. A surgicalinstrument according to claim 3 wherein said first camming slot iscurved.
 5. An ultrasonic surgical instrument comprising a) an endeffector, wherein said end effector comprises: i) an ultrasonic blade;ii) a movable clamping element disposed opposite said blade; b) anactuation mechanism operatively connected to said moveable element,wherein said actuation mechanism comprises: i) a lever arm having afirst position and a second position; ii) a first cam at a distal end ofsaid lever arm, said first cam comprising: A) a first camming pinpositioned on said lever arm; B) a first camming slot operativelyassociated with said first camming pin where in said first camming slotis positioned at an angle to a central axis of said instrument; iii) asecond cam positioned distally from said first cam, said second camcomprising: A) a second camming pin positioned on said lever arm; B) asecond camming slot operatively associated with said second camming pinwherein said second camming slot is substantially parallel to saidcentral axis, c) an actuation rod operatively connected to said leverarm and to said moveable clamping element and moveable from a firstdistal postion, to a second distal position corresponding to the firstand second position.
 6. An ultrasonic surgical instrument according toclaim 5 wherein said first camming slot is curved.
 7. An ultrasonicsurgical instrument according to claim 5 wherein said first camming slotis positioned at a camming angle of greater than twenty degrees.
 8. Asurgical instrument including a camming pivot, wherein said cammingpivot comprises: a) an actuation means for moving an end effector,wherein said actuation means comprises: i) a lever arm having a firstposition and a second position; ii) a: first camming means fortranslating arcuate motion of said lever arm to linear motion, saidfirst camming means being located at a distal end of said lever arm;iii) a second camming means for translating arcuate motion of said leverarm to linear motion, wherein said second camming means is positioneddistally from said first camming means; b) a linkage means for couplingsaid end effector to said actuation mechanism and moveable from a firstdistal postion to a second distal position corresponding to the firstand second position.
 9. A surgical instrument according to claim 8wherein said first camming means comprises a first camming pin movablypositioned in a first camming slot.
 10. A surgical instrument accordingto claim 9 wherein said first camming slot is curved.
 11. A surgicalinstrument according to claim 9 wherein said second camming meanscomprises a second camming pin movably positioned distal to said firstcamming pin in a second camming slot.
 12. A surgical instrumentaccording to claim 11 wherein said first camming slot is positioned at acamming angle of greater than twenty degrees and said second cammingslot is substantially parallel to a central axis of said surgicalinstrument.
 13. A surgical instrument including an actuation mechanismfor use in surgical instruments, wherein said actuation mechanismcomprises: a) a camming pivot means for translating arcuate motion intolinear motion, wherein said camming pivot means comprises: i) a leverarm having a first position and a second position ii) a first cammingmeans for translating a first portion of said arcuate motion into afirst portion of said linear motion, said first camming means beinglocated at a distal end of said lever arm, said first camming meanscomprising: A) a first camming pin; B) a first camming slot operativelyassociated with said first camming pin; iii) a second camming means fortranslating a second portion of said arcuate motion into a secondportion of said linear motion, wherein said second camming means ispositioned distally from said first camming means, said second cammingmeans comprising: A) a second camming pin; B) a second camming slotoperatively associated with said second camming pin; b) an actuationmeans for transmitting force from said camming pivot means to an endeffector and moveable from a first distal postion to a second distalpositions corresponding to the first and second position.
 14. A surgicalinstrument according to claim 13 wherein said first camming slot iscurved.
 15. A surgical instrument according to claim 13 wherein saidfirst camming slot is positioned at a camming angle of greater thantwenty degrees and said second camming slot is substantially parallel tosaid actuation rod.